The present invention relates to a method of producing an article ,and to the article itself, for example in pellet shape, which can simultaneously retain and destroy several classes of water pollutants.
Chlorinated compounds and inorganic oxyanions such as chromate and arsenate are major water pollutants at industrial sites, DOE facilities, and military installations. Once introduced into water, these toxic compounds tend to be only slowly degraded/transformed by natural processes. Improved methods and products are needed to trap and destroy these pollutants. Among these products are chemical filters.
Current chemical filters can be classified as either degradation filters or adsorption/precipitation filters. In degradation filters, the pollutant is converted to an innocuous form as water passes through. In adsorption/precipitation filters, pollutants are immobilized within the filter until the retention capacity is exceeded. Each of these filter types has certain disadvantages. Degradation filters require a minimum residence time to allow complete pollutant destruction. In systems with rapid water flow and/or recalcitrant pollutants, prohibitively thick filters may be required to provide the needed residence time. Adsorption/precipitation filters have a limited capacity for pollutant retention; once this capacity is exceeded, the filter needs to be regenerated or replaced. Clearly, a filter material which combines the properties of pollutant adsorption (to increase residence time) and pollutant destruction or transformation (to obviate the need for regeneration/replacement) would be very desirable.
It is therefore an object of the present invention to provide a filter material that combines the properties of water pollutant adsorption and destruction, thus overcoming the drawbacks of heretofore known filter materials used for removing pollutants from water. This new material should result in a less expensive and more efficient treatment of water polluted with chlorinated hydrocarbons and/or inorganic oxyanions.
This object, and other objects and advantages of the present invention, will appear more clearly from the following specification and examples.